Comparing the Effects of Magnesium Sulfate and Nitroglycerin on the Control of Hypertension during and after Cataract Surgery under Local Anesthesia and Intravenous Sedation

Most of the patients undergoing cataract surgery are middle-aged and older ones, accompanying high prevalence of hypertension that needs control. We compared antihypertensive effects of magnesium sulfate, as an effective drug in blood pressure control with that’s of nitroglycerine and placebo. 105 patients were allocated with simple randomization in 3 groups of 35; group 1 received stat infusion of magnesium sulfate with a dose of 30 mg/kg during 5 minutes which continued with the dose of 1 mg/kg/minute until the end of surgery; group 2 received stat infusion of nitroglycerin with the dose of 1 µg/kg during 5 minutes which continued with the dose of 0.05 µg/kg/minute; and group 3 received the solution of dextrose 5% as placebo infused with the same volume and the same infusion rate. All the groups received intravenous (IV) sedation using midazolam 0.02-0.03 mg/kg and fentanyl 1-2 µg/kg with eye drop local anesthetic tetracaine 0.5% and undergone phacoemulsification cataract surgery. Hemodynamic parameters during operation, in recovery and at the ward entrance and exit time were recorded. There was no significant difference between the mean diastolic blood pressure among all the groups (P = 0.49). The mean systolic and mean arterial (MAP) blood pressures during the operation at the 30th minute, and then at 15th and 30th minutes in recovery and also at the ward entry and exit time, had lower amounts in magnesium sulfate and nitroglycerin groups compared to placebo group (P = 0.019). But, there was no significant difference between the magnesium sulfate and nitroglycerin groups (P = 0.060). The mean heart rate was not significantly different at any of the studied times among 3 groups (P = 0.170). The usage of magnesium sulfate in patients with hypertension is effective during and especially after phacoemulsification surgery cataract under local anesthesia just like nitroglycerine; but has no significant effect on the postoperative pain.